Propane Power is Here!

It Finally Happened and How Great is That!?!

One highlight of the Miami show was in one of the engine manufacturer tents. And if any of you know some of the stuff I have been doing the past number of years, you will understand my excitement. The short story goes something like this: I had been seeing a lot of issues with gasoline-powered outboards in recent years, from our 150-hp Mercury outboard on our Boston Whaler to small dinghy engines among the cruising fleet of our yacht club. No one seems to escape the evil clutches of ethanol and all it brings to boating. I sold the Whaler out of frustration, but thought perhaps we could do something about this.

Howard Brooks and I teamed up to see if we could find an alternative to gas outboards. Howard was thoroughly disgusted with his gas outboards, which never ran well soon after taking them in for service. He eventually bought a small electric Torqueedo for his dinghy, but the electric outboard is somewhat limited in terms of performance and range. Howard and I wanted to see if we could find a readily available fuel that would work better in an internal combustion engine, so we decided to play with propane. Compressed natural gas (CNG) would be even better, not coming from petroleum, but as of 2017, it is not easy to find anywhere.

The project became our little research company, Marine Green.

We built our first prototype on a Yamaha 4hp that had not run in years, but we soon had it operating off a one-pound propane bottle. It likely produced less than a full four horsepower, but it worked, proved reliable, and the one-pound bottle lasted an hour at full throttle. We next moved up to a new Mercury 6hp engine, and later a 9.9hp electric-start Mercury.

We never expected we could manufacture these engines, but hoped that some company somewhere would pick the concept up. A number of videos and press releases later, and a growing database of interested people wanting to know more, it got noticed. Lehr manufactures propane-powered landscape equipment, and the company was able to adapt its propane solutions to the outboard market. Lehr introduced a line of small outboard engines to the boating market. While I don't know for certainty that Marine Green spawned the Lehr line, rather than a chance coincidence, but as we had already filed a patent for the propane fuel delivery system, I knew we were on the leading edge.

For all of the reasons you will read below, I really hoped that one of the big engine companies would get into the game, as the environmental impacts of this fuel choice are that huge. So it was simply thrilling to see Tohatsu at Miami introducing a small propane outboard. Tohatsu also builds dinghy-sized outboards for Nissan and Mercury. It is a giant in the small outboard engine manufacturing world.

Many cruisers already carry propane for cooking on their boats. Getting tanks refilled often means a trip out of the marina, often a mile or more away. With more people using propane outboards, it won't be long before fuel docks offer propane along with diesel and gasoline.

Below are talking points from my 2009 research into the viability of propane power:


Size of Marine Outboard Market

Outboard boats accounted for nearly half on all boats in use with more than 8.3 million on the water in 2008, out of 16.93 million total. Outboard boats are most popular, making up nearly two-thirds of registered powerboats in 2007, and nearly 95 percent of all registered powerboats in 2008 were less than 26 feet.

The proportion of the American adult population who went boating in 2008 was 30.5 percent. Ten-year average number of new outboards sold in U.S. is 301,870 per year. Of these new outboard sales, according to 2008 sales percentages:

  • Under 4hp: 12,075 engines (4%) – average street price $862

  • 4hp to 9.9hp : 43,167 engines (14.3%) – average street price $1,676

  • 10hp to 29.9hp: 36,224 engines (12%) – average street price $2,687

  • Total of 1hp to 29.9hp range: 91,467 engines



Environmental Impact of Current Marine Outboard Engines

It has been estimated that operating a boat with an outboard engine for one hour can make as much air pollution as driving a car for 800 miles.

Marine engines are among the greatest contributors of hydrocarbon (HC) and oxides of nitrogen (NOx) pollution in the U.S.

In some regions of the U.S., fuel from outboard engines is the primary cause of federal designations of impaired water bodies.

Engine emissions can produce ground-level ozone and smog

Carbureted two-stroke engines pass as much as one third of the fuel passing through the combustion chamber unburned, releasing hydrocarbons, nitrogen oxides, and toxic constituents of gasoline directly into the environment

Hydrocarbons and nitrogen oxides released into the air contribute to the formation of ground-level ozone, which can irritate the respiratory system and aggravate respiratory conditions such as asthma.

Gasoline released into our waterways contribute to elevated levels of benzene, methyl tertiary-butyl ether (MtBE), and other gasoline components

According to EPA studies, marine engines are one of the highest contributors to hydrocarbon, NOx, particulate matter, and carbon monoxide emissions, with the highest contributor being small spark-ignited non-road engines under 25hp (19kW), such as those found in lawnmowers, generators, and garden equipment.

Beginning in 1998, lower pollution outboards have been introduced into the marketplace, but the extreme durability of marine outboard engines (some last over 40 years) means the benefits of these lower pollution engines won’t be fully realized until 2025.

New, stricter EPA emissions standards require a significant reduction.


Spoiling Boating with Ethanol

Legislation introduced ethanol-enhanced fuel in 2004 with a 10 percent concentration (E10). A property of ethanol is its ability to attract and absorb water.

Ethanol saturated with water separates from gasoline, forming two solutions. This is called phase separation. No engine will run on the water-saturated ethanol, which also is highly corrosive and sits at the bottom of a fuel tank.

Current legislation is trying to increase the ethanol concentration to 15 percent, and this E15 fuel will only increase the problematic nature of this fuel.

E10 and E15 fuels can not sit unused for a long period; the useful shelf life is between 90 days up to perhaps one year. For the average boat owner this can cause difficulties, as small boat use often dictates keeping stored engine fuel from season to season.

When it is found to have gone bad it is often improperly disposed of.

With the economy and higher fuel costs, many boat owners don’t use their boats as often as they used to, further adding to the problem. Lack of boat use promotes phase separation, especially when tanks are not kept full.

Ethanol has greatly reduced the safety factor of marine engines, threatening people out on the water with engines that quit. This is a serious safety issue of reduced reliability.

The Propane Option

Propane (also known as liquefied petroleum gas, or LPG) is a mixture of liquefiable gaseous hydrocarbons that include propane, butane, isobutene, propylene, and butylenes.

Propane is a by-product of oil refining or by stripping natural gas.

Below 42 degree Centigrade, propane is a liquid. When it changes to a vapor, it increases in volume 270 times.

Propane has been rated as being 54 percent safer than gasoline as a fuel source by the Liberty Mutual Insurance Company. Its storage tank is far more substantial than a gasoline tank and is not likely to be punctured in an accident.

A well-tuned propane powered engine does not require any emission controls (such as catalytic converters) because it is an inherently cleaner fuel than gasoline.

Propane does not produce carbon deposits in the combustion chamber, nor does it contaminate engine oil. Engine life is greatly enhanced with longer periods of oil changes and spark plug replacement.

With propane, there is no chance of fuel spilling into our waterways.

Propane combustion is so clean it is used on vehicles inside buildings.

Growing concerns about climate change and the environmental impact of conventional fuels have focused attention on technologies and fuel sources to reduce greenhouse gas (GHG) emission. Propane has been approved by the EPA as a clean alternative fuel, producing lower GHG emissions than gasoline or ethanol fuels.

Of the primary markets for propane in the U.S. today, only 4 percent of total gallons sold are used for internal combustion engines, which are mainly forklifts, commercial grounds equipment, and fleet vehicles. The majority of primary markets include residential, agricultural, commercial, and chemical industrial.



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